A vehicle seat in which a dynamic damper is structured by integrally supporting a mass body within a pad is disclosed in following Patent Document 1. Further, a headrest in which a dynamic damper is structured by providing an elastic resin material that is injected into a molding bag and foam-molded and a weight that is fixedly placed with respect to the molding bag, is disclosed in following Patent Document 2. In these prior art, because vibrations are damped by the dynamic damper, the NV performance (noise and vibration performance) can be improved.